摘要
超高镍层状材料LiNi_(0.92)Co_(0.04)Mn_(0.04)O_(2)(简称NCM92)因其具有较高的能量密度和价格优势,已成为锂离子电池重要的正极材料来源之一。然而,由于该材料的界面不稳定和不可逆相变,商业应用面临特别是在高截止电压下快速的容量衰落和严重的结构退化的问题。本研究设计了一种ZrO_(2)/Li_(2)ZrO_(3)双包覆层改性超高镍单晶正极材料,同时材料表面均匀掺杂有Zr元素,通过双包覆层协同策略显著增强了正极的高压性能和结构稳定性。研究结果表明,ZrO_(2)/Li_(2)ZrO_(3)双包覆层可以有效缓解超高镍正极材料H2-H3相变的不可逆性,提高力学稳定性和界面稳定性,同时表面Zr掺杂进入晶体结构中的TM层与Li位抑制Li/Ni混排并扩宽了晶格间距,ZrO_(2)/Li_(2)ZrO_(3)双包覆层与Zr掺杂改性的材料(NCM92-Zr)展现出优异的电化学性能,在0.5 C(200 mA·g^(-1))电流密度下,2.75~4.4 V电压范围内循环150圈后仍有155.2 mA h g^(-1)的放电比容量,容量保持率高达75.5%。此研究为在高截止电压下超高镍正极的复杂机制和改进的结构稳定性提供了新的思路。
Ultra⁃high nickel layered material LiNi_(0.92)Co_(0.04)Mn_(0.04)O_(2) (Abbr.NCM92)has become one of the important cathode sources for lithium⁃ion batteries due to its high energy density and price advantages.However,a key challenge for commercial applications is rapid capacity fading and severe structural degradation,especially at high cut⁃off voltages,resulting from interface instability and irreversible phase transitions.In this study,a ZrO_(2)/Li_(2)ZrO_(3)double coating modified ultra⁃high nickel single crystal cathode material was designed,and the surface of the material was uniformly doped with Zr element,which significantly enhanced the high cut⁃off voltages performance and structural stability of the cathode electrode through the synergic strategy of double coating.The results show that the ZrO_(2)/Li_(2)ZrO_(3) double coating can effectively alleviate the irreversibility of H2-H3 phase transition of the ultra⁃high nickel cathode material,improve the mechanical stability and interface stability.At the same time,the TM layer and Li site of the surface Zr doping into the crystal structure inhibit the Li/Ni mixing and widen the lattice spacing.As expected,ZrO_(2)/Li_(2)ZrO_(3)double⁃coated with Zr⁃doped modified materials(NCM92-Zr)demonstrated excellent electrochemical properties at 0.5 C(200 mA·g^(-1))current densities,after 150 cycles in the voltage range of 2.75~4.4 V,the discharge specific capacity of 155.2 mAh·g^(-1)remains,and the capacity retention is 75.5%.The study provides new insights into the complex mechanisms and improved structural stability of ultra⁃high nickel cathode at high cut⁃off voltages.
作者
李西安
张龙华
LI Xi'an;ZHANG Longhua(Henan Intelligent Safety Engineering Research Center for Rail Transit,Zhengzhou 450018,China;Locomotive Vehicle Department,Zhengzhou Railway Vocational Technical College,Zhengzhou 450052,China)
出处
《中国有色冶金》
CAS
北大核心
2023年第3期116-123,共8页
China Nonferrous Metallurgy
基金
国家自然科学基金资助项目(52175123)
河南省2023年职业院校省级骨干教师资助项目
郑州铁路职业技术学院2021年青年骨干教师培养计划项目
郑州铁路职业技术学院科研项目(2023KY020)。
